An image processing device has been known, which is able to recognize objects (obstacles) existing in the images that are captured by a camera such as a CCD camera. Japanese Published Patent Application 9-91438 discloses an apparatus for detecting mobile objects applicable to a robot and the like. The apparatus employing a camera, which is mounted on a mobile positioning mechanism and rotated about a vertical axis, stores images captured by the camera and detects the mobile objects introducing differential processing for the images. In this method the direction of camera is controlled by rotating the camera so that the center position of a camera lens can be fixed.
However, the apparatus for detecting mobile objects described above still poses a problem that a heavy load for image processing cannot be avoided since processing is conducted generally for all captured images in order to recognize mobile objects. Furthermore, if the apparatus is applied to a mobile robot or vehicle, it still leaves much to be desired in terms of recognition of obstacles such as mobile objects. The reason for this is that the position of a camera mounted on a mobile apparatus varies, so that the distances between the apparatus and stationary objects (obstacles) such as walls or fences always vary accordingly, which makes it difficult to distinguish mobile objects from the stationary ones and focus on recognition of the former.